hgweb: inline caching() and port to modern mechanisms
We only had one consumer of this simple function. While it could be
a generic function, let's not over abstract the code.
As part of inlining, we port it off wsgirequest, fix some Python 3
issues, and set a response header on our new response object so it
is ready once we start using it to send responses.
Differential Revision: https://phab.mercurial-scm.org/D2785
from __future__ import absolute_import
import pkgutil
__path__ = pkgutil.extend_path(__path__, __name__)